Afghanite - Encyclopedia

    Class : Silicates
    Subclass : Tectosilicates
    Crystal System : Trigonal
    Chemistry : (Na,Ca,K)8(AlSiO4)6(SO4,Cl2,CO3)3 0.5H2O.
    Rarity : Rare

Afghanite is a feldspathoid commonly accompanied by minerals from the sodalite family. It owes its name to its country of discovery : Sar-e-Sang in Afghanistan. It is a mineral of metamorphic limestones in contact with alkaline granites or syenites. It forms elongated azure blue hexagonal prisms ending in pyramids, its microcrystals can also be colorless. Although rare, it is a mineral that finds uses in jewelry and can be cut into faceted gems. Photo © Joe Budd

Afghanite in the World

Afghanite was discovered in 1968 in the lapis lazuli mine of Sar-e-Sang in Afghanistan (province of Badakhchan), which produced the best crystals in the world but also the only ones of macrometric sizes : doubly-terminated prisms to more 6 cm long. It was then described in Germany (Caspar quarry), in Italy (Lazio and Tuscany), in the Pamirs (Tajikistan) and near Lake Baikal in Siberia. These localities, on the other hand, produced only transparent microcrystals.

Afghanite in France

This mineral has not been described in the French underground.

Twinning

No known twin for this mineral species.

Fakes and treatments

Afghanite crystals are often released from their acid matrix, however the acid also etches the Afghanite which then takes on a molten appearance. If the sample is subsequently not properly neutralized, it whitens. Crystals not cleared with acid are rare.



Hardness : 5.5 to 6
Density : 2.6
Fracture : Conchoidal
Trace : White




TP : Translucent
RI : 1.523 to 1.529
Birefringence : 0.006
Optical character : Uniaxial +
Pleochroism : Low
Fluorescence : Orange


Solubility : Hydrochloric and sulfuric acids

Magnetism : None
Radioactivity : None

ReCaptcha

This service is used to secure web forms of our website and required if you want to contact us. By accepting it you agree to Google's privacy policy: https://policies.google.com/privacy

Google Analytics

Google Analytics is a service used on our website that tracks, reports traffic and measures how users interact with our website content in order for us to improve it and provide better services.

Facebook

Our website allows you to like or share its content on Facebook social network. By activating and using it you agree to Facebook's privacy policy: https://www.facebook.com/policy/cookies/

YouTube

Integrated videos provided by YouTube are used on our website. By accepting to watch them you agree to Google's privacy policy: https://policies.google.com/privacy

Twitter

Integrated tweets and share services of Twitter are used on our website. By accepting and using these you agree to Twitter's privacy policy: https://help.twitter.com/en/rules-and-policies/twitter-cookies

PInterest

Our website allows you to share its content on PInterest social network. By activating and using it you agree to PInterest's privacy policy: https://policy.pinterest.com/en/privacy-policy/